Thyroid Disorders Flashcards
`How does hypothyroidism present?
- Weight Gain
- Cold intolerance
- Brittle nails, thin/dry skin & hair
- Hyporeflexia, slow speech
- Lethargy & low mood
- Constipation
- Bradycardia
- Heavy periods
Severe cases can cause puffy face, large tongue, hoarseness and coma
How does hyperthyroidism present?
- Weight loss
- Heat intolerance
- Muscle weakness
- Hyperreflexia
- Frequent bowel movements
- Palpitations
- Light periods
- Sweaty palms
- Thyroid eye symptoms (bulging)
- Anxiety/irritibility
How does gender affect thyroid disease?
Both hyper and hypothyroidism are much more common in women
What are the types of Hypothyroidism?
Primary
Subclinical
Secondary
What causes congenital Hypothyroidism?
- developmental problems e.g. agenesis
- Dyshormogenensis (autosomal recessive condition preventing TH production)
What causes acquired Primary Hypothyroidism?
- Autoimmune (hashimoto’s) thyroiditis
- Iatrogenic
- Chronic Iodine Deficiency
- Post-subacute thyroiditis
What can cause secondary or tertiary hypothyroidism?
- Pituitary tumours
- Craniopharyngioma
- Pituitary surgery/radiotherapy
- Sheehan’s Syndrome
- Isolated TRH deficiency
What is Sheehan’s Syndrome?
Post-partum ischaemic necrosis of the pituitary due to blood loss/hypovolaemic shock of childbirth
Its a potential cause of secondary hypothyroidism
List some iatrogenic causes of primary hypothyroidism?
Post op
Radioactive Iodine or Anti-Thyroids
Amiodarone (Sub-acute thyroiditis)
RT for H/N cancer
What tests would you run for suspected hypothyroidism?
- TFTs i.e. TSH & fT4
- Anti-Thyroid Peroxidase Antibodies (Hashimotos)
- FBC
- Lipids
- Serum Na+
- Muscle enzymes, ALT & CK
- Prolactin
Explain why youd do each test for hypothyroidism?
FBC - Raised MCV (RBC size) Lipids - Hypercholesterolaemia Na+ - Hyponatremia due to excess ADH from hypothyroidism Muscle enzymes, ALT & CK are all raised Prolactin - Hyperprolactinaemia
How will TFT’s Appear for each class of Hypothyridism?
Primary - Low fT4 but high TSH
Secondary - Low fT4 & low or normal TSH
Subclinical - Normal fT4 & High TSH
What do we use to manage hypothyroidism?
Levothyroxine (T4) tablets
Explain the dosing of Levothyroxine?
Start at 50mcg/day
Titrate up to 100mcg/day after 2 weeks
Keep increasing until their TSH (primary disease) or fT4 (Secondary Disease) is normal.
What special cases affect how you use Levothyroxine?
- IHD needs to be started lower and titrated slowly as it can trigger Angina
- Pregnant women need more T4
- Myxedema Coma needs IV T3
- Post-partum Thyroiditis needs to have the meds removed for 6 weeks and TFTs measured to see when it abates
Should we treat subclinical hypothyroidism?
Only if:
- TSH >10
- > 5 + Antibodies
- TSH elevated + symptoms (temporary trial therapy for symptom improvement)
- Pregnant or planning pregnancy